The purpose of this study is to determine the cause of low blood pressure in selective patients who have problems with their involuntary (autonomic) nervous system. These patients frequently have had symptoms throughout their life, and their disorder might have a genetic basis. The biochemical, physiological and pharmacological procedures in this study should help us define the problem and perhaps lead to more effective treatment.

Questionnaires and computer tasks, an EEG and an MRI may be used to assess brain function.

Procedure: Bicycle Exercise Test

Blood pressure and heart rate may be monitored while exercising on a stationary bicycle.

Eligibility

Ages Eligible for Study:

12 Years to 70 Years (Child, Adult, Senior)

Sexes Eligible for Study:

All

Accepts Healthy Volunteers:

No

Criteria

Inclusion Criteria:

severe orthostatic hypotension and other autonomic symptoms but do not meet criteria for standard diagnosis

non-smokers

drug-free

able to give informed consent

free of pulmonary, renal, hematopoietic, hepatic and cardiac disease

Exclusion Criteria:

medications affecting the autonomic nervous system

any chronic illness

anemia (Hct<30)

women of childbearing age who are pregnant or nursing

smokers

Contacts and Locations

Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study.
To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below.
For general information, see Learn About Clinical Studies.

Please refer to this study by its ClinicalTrials.gov identifier: NCT00748059